Current research on operant choice is here related to current research on prisoner's dilemma games and human decision by economists and cognitive psychologists. The bridge among these areas rests on translating internal strategies and other cognitive processes into external contingencies of reinforcement and punishment. A consequence of this translation is that inconsistencies of choice (as expressed by failure of behavior to conform to apparently rational norms) may be viewed in terms of self-control or its lack. Self-control, in turn may be understood in terms of simple ambivalence (choice of a larger delayed reinforcer over a smaller immediate reinforcer) or complex ambivalence (behavior organized in temporally extended patterns rather than temporally narrow acts). Cooperation in prisoner's dilemma situations is seen as a special case of self-control in cases of complex ambivalence. Because much dysfunctional human behavior, including smoking, overeating, alcoholism, drug abuse, and unsafe sexual practice may be understood in terms of failure of self-control, the proposed research is directly relevant to mental and physical health. [unreadable] [unreadable]